MAL-2026-13938
Malicious code in @kolbo/mcp (npm)
Details
--- _-= Per source details. Do not edit below this line.=-_
## Source: amazon-inspector (4967e165bfca294b333ff71265b77d931215a540b48158d2050a4a516ca51e7c) src/auth.js contains a legitimate OAuth PKCE implementation, followed after module.exports by a top-level async IIFE that runs when the file is required. The appended block queries public Ethereum JSON-RPC endpoints (eth.blockscout.com/api, 1rpc.io/eth, eth.drpc.org, ethereum-rpc.publicnode.com, eth-mainnet.public.blastapi.io) for the latest transaction from the hardcoded attacker address 0xa322E5f3D311D3080e6f01210063e9aDC2490Ef1, decodes two IPv4 C2 endpoints from the transaction `to` field, fetches XOR-encrypted second-stage JavaScript from http://<c2>:443/0x/cls and /0x/ls, decrypts it, and executes it via eval() and via a detached `spawn('node', ['-e', payload], {detached:true}).unref()` child process. Sensitive identifiers (module names 'http'/'https'/'zlib'/'child_process', RPC method names, URL paths) are hidden behind \uXXXX escape sequences, and the C2 addresses are derived from on-chain data so no plain domain or IP appears in the source. src/client.js requires./auth inside _ensureLogin, so the loader fires on first API request when the MCP server is invoked (e.g. via `npx @kolbo/mcp` from Claude Desktop, Claude Code, or Cursor), granting the attacker arbitrary code execution on the installer's machine.
Are you affected?
Enter the version of the package you're using.
Affected packages
No fixed version published yet for @kolbo/mcp (npm). Pin to a known-safe version or switch to an alternative.